Tasmania cooked by marine heatwave powered by climate change

Yet more information suppressed by the powers-that-be in New Zealand.

Date:July
17, 2017Source:University
of New South WalesSummary:Climate
change has warmed the waters east of Tasmania at four times the speed
of the global average. But the heatwave of the southern summer of
2015/2016 was something exceptional, damaging fisheries and bringing
new species to the island. It's a sign of things to come, say the
researchers examining these events.

Climate
change was almost certainly responsible for a marine heatwave off
Tasmania's east coast in 2015/16 that lasted 251 days and at its
greatest extent was seven times the size of Tasmania, according to a
new study published today in Nature Communications.

The
marine heatwave reduced the productivity of Tasmanian salmon
fisheries, led to a rise in blacklip abalone mortality, sparked an
outbreak of Pacific Oyster Mortality Syndrome and saw new fish
species move into Tasmanian waters.

At
its peak intensity, waters off Tasmania were 2.9°C above expected
summertime temperatures.

Lead
author from the ARC Centre of Excellence for Climate System Science
(ARCCSS) Dr Eric Oliver said marine heatwave events of this kind were
likely to increase in the future because of climate change.

"We
can say with 99 per cent confidence that anthropogenic climate change
made this marine heatwave several times more likely, and there's an
increasing probability of such extreme events in the future," Dr
Oliver said.

"This
2015/16 event was the longest and most intense marine heatwave on
record off Tasmania."

The
research team led by scientists from ARCCSS and the Institute for
Marine and Antarctic Studies (IMAS) at the University of Tasmania, in
collaboration with the CSIRO and the Australian Institute of Marine
Science, found the heatwave was driven by a surge of warm water in
the East Australian Current, which has been growing stronger and
reaching further south in recent decades.

The
area off the east coast of Tasmania is already known as a global
warming hotspot with temperatures in this region warming at nearly
four times the global average rate.

Co-author
Associate Professor Neil Holbrook from IMAS said it was vital to
monitor and research these marine heatwaves because if identified
early it would allow fisheries and aquaculture industries to adapt
and manage their resources.

"The
evidence shows that the frequency of extreme warming events in the
ocean is increasing globally," Associate Professor Holbrook
said.

"In
2015 and 2016 around one quarter of the ocean surface area
experienced a marine heatwave that was either the longest or most
intense recorded since global satellite-records began in 1982.

"Studying
these events plays an important role in helping industries,
governments and communities to plan for and adapt to the changes and
their growing impacts on our environment and ecosystems,"
Associate Professor Holbrook said.

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